Decouple root visitors from object visitors.

src/snapshot/deserializer.h

Index: src/snapshot/deserializer.h
diff --git a/src/snapshot/deserializer.h b/src/snapshot/deserializer.h
index 66025fe08c759c1a2f559904323dcb75e6c4241e..a56adb67d48b16fbac6dc5f3b4e1afd864ee76a0 100644
--- a/src/snapshot/deserializer.h
+++ b/src/snapshot/deserializer.h
@@ -63,12 +63,10 @@ class Deserializer : public SerializerDeserializer {
   }
 
  private:
-  void VisitPointers(Object** start, Object** end) override;
+  void VisitRootPointers(Root root, Object** start, Object** end) override;
 
   void Synchronize(VisitorSynchronization::SyncTag tag) override;
 
-  void VisitRuntimeEntry(RelocInfo* rinfo) override { UNREACHABLE(); }
-
   void Initialize(Isolate* isolate);
 
   bool deserializing_user_code() { return deserializing_user_code_; }